Image forming apparatuses such as MFPs (Multi-Function Peripherals) are generally equipped with plural CPUs (Central Processing Units). One example of a way to use plural CPUs in such apparatuses is that, in a case of an image forming apparatus equipped with two CPUs, one of the CPUs is exclusively assigned to control of the operation of a print engine (including control of printing and drive control of mechanical components of the image forming apparatus) which needs real-time processing at an extremely high level, and the other is assigned to control of the entire operation of the image forming apparatus except for the print engine (including image processing, video output and control of user interface).
In recent years, image forming apparatuses employing plural CPUs which share a bus and a memory are coming into the market. For example, some image forming apparatuses employ a multi-core CPU or a multi-core processor including multiple cores (independent processing units) which are assigned to respective types of control as described above. Such image forming apparatuses have the advantage in cost, because plural cores share a bus and a memory, and further have the advantage in handling abnormalities occurring in the operation so that the apparatuses can easily perform error recovery processing, because each of the cores of the multi-core CPU can monitor the other core easily. For example, in a situation that input of image data into the print engine stops for a certain period of time for some reason, such apparatuses can totally eject a sheet or sheets on which image data was being printed so as not to leave the sheet or sheets inside the body of the print engine.